1. Field of the Invention
This invention relates to blends containing polyamides and is more particularly directed to blends of certain aromatic-aliphatic polyamides and impact modifiers and to methods of preparation of said blends.
2. Description of the Prior Art
A variety of blends of impact modifiers and polyamides have been described in the prior art. In particular it is known that nylon-6, nylon-6,6 and a series of related polyamides can be blended with various types of polymeric impact modifiers to enhance the impact resistance of these polymers. Illustrative of such blends are those described in U.S. Pat. Nos. 3,974,234; 4,167,505; 4,221,879; 4,247,665; 4,321,336; 4,338,406; 4,362,846; 4,381,371; 4,405,748 and 4,423,186.
A series of polyamides has recently been introduced to the commercial marketplace in which the acid moiety of the polyamide is derived from a mixture of aliphatic dicarboxylic acids or a mixture of an aliphatic and an aromatic dicarboxylic acid and the amine or amide forming moiety is derived from a diamine or diisocyanate which is aromatic in nature. These polyamides are characterized by ease of melt processing, excellent physical properties and, in certain cases, by ease of conversion to the crystalline state. Although these products mainly exhibit good impact resistance, we have now found that this particular property can be significantly increased by introducing into the polymer, as a blend, a minor amount of certain polymeric impact modifiers. We believe that the degree of enhancement of the impact resistance of the polyamides achieved in this manner is significantly greater than would be expected based on the known properties of the two components.